Generally, in a lithography process for manufacturing devices, such as a semiconductor device or a liquid crystal display device, an exposure apparatus is used to transfer a predetermined pattern formed in a mask, such as a reticle or a photomask, onto a substrate, such as a wafer or a glass plate, to which resist is applied, via projection optical system. The transferred pattern is miniaturized to satisfy the demand for higher integration. Thus, in addition to improving the exposure accuracy and resolution of an exposure apparatus, the alignment accuracy of optical elements that are included in the exposure apparatus must also be improved.
However, in an exposure apparatus of the prior art, vibrations generated inside and outside the exposure apparatus may be transmitted to optical elements (lenses, mirrors, etc.) included in the exposure apparatus. The transmission of vibrations may change the positions or attitudes of the optical elements and thereby lower the alignment accuracy of the optical elements. Therefore, an exposure apparatus including a damper mechanism having a vibration damping function has been proposed. Refer to, for example, Patent Document 1.
In the exposure apparatus described in Patent Document 1, an intermediate block is supported on a fixed block, which serves as a fixed portion fixed in a projection optical system, by an position adjustment mechanism including a parallel link mechanism. The intermediate block holds optical elements. The position adjustment mechanism adjusts the position and tilt of the intermediate block with six degrees of freedom. The position adjustment mechanism drives and moves the optical elements together with the intermediate block. This adjusts the position and tilt of the optical elements.
The intermediate block supports an additional mass via a bearing. The intermediate block faces toward the additional mass in a state spaced from the additional mass. A plurality of magnets are arranged on the opposing surfaces of the intermediate block and the additional mass so that they attract one another. A conductor plate supported by the fixed block (or the intermediate block) is arranged between the magnets of the intermediate block and the magnets of the additional mass. During the propagation of vibrations, the conductor plate and the magnets move relative to one another and generate eddy current. The eddy current is used to generate force for damping the vibrations. Thus, the conductor plate and the magnets function as a magnetic damper.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-340372 (US Patent Application Publication No. 2004/212794).